Wont idle or even drive without giving it throttle. Dies as soon as i'm off the pedal. Will run normal if i'm on the throttle. All new plugs, wires, coil. I hooked up my charger tonight and within 10mins it said full charge. Battery cables appear to be fine. Where to start?

Describe in finer terms. Not idling at idle ONLY and dies when motor gets down AROUND IDLE SPEED is dead IAC. If dead higher up the rpm range something different. Does it run when you slightly hold down the throttle to imitate the IAC while say sitting at traffic light? If so then again IAC.

Not battery if running fine at higher throttle settings and engine speeds. The alternator output would be more important there anyway.

Idle air control valve. You should also check the PCV vacuum line as it is the cause of idle woes, though not specifically this woe. The PCV line will collapse under idle causing low idle, and if there are cracks in the line you'll have high idle as well as popping, hiccuping, and other running issues at higher rpm. The rubber decays after about 10 years regardless of mileage.

It could be bad o2 sensor. My girlfriends car had bad o2 sensors and when the battery got changed and reset the computer it would not idle unless gassed and it had two bad o2 sensors. It wasn't reading the proper air/fuel ratio. You would likely have a CEL for that though so I would be sure it is that before replacing.

Thanks for the replys guys! I'll try the IAC and check the pcv report back.

I do probably need a new o2. Car now has 105k and i dont know if the previous owner replaced it yet.

Well, like Bringler said, if you don't have a check engine light on you can pretty safely assume they're working fine. They don't necessarily go bad either, the two other Foci in my family both have over 200K miles, and to my knowledge neither has ever had o2 sensor problems.

amc49, was it you that had IAC problems recently and actually dissasembled the thing for a thorough cleaning? Somebody did that fairly recently and went into a good amount of detail about it, I don't know if it fully solved the problem or not.

If you end up getting a new one, Hitachi sells one that's cheaper than others, I used it on one of the other cars and it works fine.

Ok, I took at look at the location of the IAC and holy crap, i didn't want to mess with that.

So, I ended up pulling off the intake tube and spraying an entire bottle of intake cleaner down the throttle body where the port is for the IAC (with the car running of course). That seems to have cleaned it out enough to where it idles good now. All is well now. :)

Register Now

In order to be able to post messages on the Ford Focus Forum, Ford Focus ST Forum, Ford Focus RS Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:

Password

Please enter a password for your user account. Note that passwords are case-sensitive.

Password:

Confirm Password:

Email Address

Please enter a valid email address for yourself.

Email Address:

What I Drive

Year, color, and model of your car. Example: 2003 Pitch Black ZX3

Name

Your real name.

City

State

Country

Insurance

Please select your insurance company (Optional)

Log-in

User Name

Remember Me?

Password

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.